qm is a script to manage virtual machines with Qemu/Kvm. You can create and destroy virtual machines, and control execution (start/stop/suspend/resume). Besides that, you can use qm to set parameters in the associated config file. It is also possible to create and delete virtual disks.
All configuration files consists of lines in the form
PARAMETER: value
See man vm.conf for a complete list of options.
Configuration files are stored inside the Proxmox cluster file system, and can be access at /etc/pve/qemu-server/<VMID>.conf.
The default for the keyboard option is read from
/etc/pve/datacenter.conf.
Online migrations and backups (vzdump) set a lock to prevent incompatible concurrent actions on the affected VMs. Sometimes you need to remove such a lock manually (e.g., after a power failure).
qm unlock <vmid>
Create a new VM with 4 GB IDE disk.
qm create 300 -ide0 4 -net0 e1000 -cdrom proxmox-mailgateway_2.1.iso
Start the new VM
qm start 300
Send a shutdown request, then wait until the VM is stopped.
qm shutdown 300 && qm wait 300
Same as above, but only wait for 40 seconds.
qm shutdown 300 && qm wait 300 -timeout 40